Electrons in quantum materials are wavelike, displaying both tunneling and interference. They spontaneously fluctuate among states, and their wavefunctions are entangled over macroscopic length scales. The quantum revolution will exploit these properties in new technologies as diverse as sensors with unprecedented sensitivity, logic gates enabling quantum computation, and new devices that transport heat and electricity very differently from conventional materials. Of central importance is the tension between quantum fluctuations that limit the stability of magnetically ordered states T=0, and strong electronic interactions that favor moment formation and ordered phases. These novel phases host fundamental excitations that are wholly unlike those of conventional insulators and metals, and are themselves unstable to the formation of other phases, notably unconventional superconductivity. Investigating these wholly novel types of phase transitions requires the identification of new materials where different aspects can be isolated, as well as experimental tools that can probe the spatial and dynamic correlations in more powerful ways.